This invention relates to a vital driver, where the term "vital" is understood to have its meaning as utilized by those skilled in the art of railway signaling. Generally "vital"means that should components fail, the device is left in a non-operative state, so as not to signal an erroneous condition. As can be understood, where the driver is used to provide a source of power to a lamp, it is desirable that in a vital device should a component fail, the lamp is left unlit, as opposed to remaining lit which may signal a condition that does not, in fact, exist. It has been common practice to use a vital relay as a driver for lamp loads in the railway signal industry. Vital relays are well known and are sophisticated electromechanical devices in which should the relay fail, the contacts operate in a way to open the circuit and interrupt power to the light bulb. Some of the disadvantages of utilizing vital relays are size, costly and the fact that relays are mechanically operated. Vital relays become especially costly and bulky where a large number of lamps are to be driven in a given location. It would, therefore, be desirable if large racks of vital relays used for lamp-driving application could be replaced with smaller solid-state devices having a considerably reduced footprint. Various contact interlocking schemes with vital relays can be used for obtaining different levels of vitality. It is, therefore, desirable to have a relatively simple low-cost small solid-state device that can act in a vital manner to power loads such as lamps. Typically, it is desired to operate the lamps with a sinusoidal AC current, while providing a control signal that is low voltage DC. The lamps that are to be driven will generally operate from a lower voltage AC, and it is common to use step-down lamp transformers to obtain low voltage AC power.